What is Polyester - Manufacturing of Polyester
The process of manufacturing polyester is fascinating. It is an artificial man-made fiber. Polyesters are generally manufactured from petroleum from which the constituent acids and alcohols are derived.
There are three steps in the synthesizing of polyester.
- Condensation Polymerization: When acid and alcohol are reacted in a vacuum at high temperatures it results in condensation polymerization. Once the polymerization has occurred the material is extruded onto a casting trough in the form of a ribbon. Once cool, the ribbon hardens and is cut into chips.
- Melt-spun Fiber: The chips are dried completely. Hopper reservoirs are then used to melt the chips. A unique feature of polyester is that it is melt-spun fiber. The chips are heated, extruded through spinnerets and cools upon hitting the air. It is then loosely wound around cylinders.
- Drawing: The fibers consequently formed are hot stretched to about five times their original length. This helps to reduce the fiber width. This fiber is now ready and would into cones as filaments. It can also be crimped and cut into staple lengths as per requirements.
Different Types Of Polyester
There are several processes that can be carried out on the base polyester fiber. These processes add dimension to the polyester fiber as required for various end uses.
Polyester is a bright fiber by nature. However, it can be made dull or semi-dull by adding a delusterant. By changing the shape of the spinneret also, the hand and the strength of the fiber can be changed. Most spinnerets are circular. However, square, oval and bean-shaped fibers are also produced sometimes. Hollow fibers can also be created.
Polyester fiber is generally drawn to about five times its original length. However, drawing it out further makes it thinner. This is how the latest microfibers are being manufactured. Dyeing can give desired colors of polyester fiber. Normal polyester fiber is long and smooth. Crimping it can give the fiber more bulk and texture and increase its insulation capabilities.
Once the polyester fiber is ready it is used to make filament and spun yarns. The yarns can be blended with other fibers to make various blended fabrics.
Polyester and cotton are a popular combination. Wool and rayon are also blended with polyester to make fabrics.